Preheat oven to 350 degrees. In a large casserole or Dutch oven, melt butter over medium heat. Add onions, carrots, celery and garlic. Cook, stirring occasionally, for 10-15 minutes, or until the vegetables are lightly colored. Remove the casserole from heat. Season the veal pieces with salt and pepper and dredge in flour. In a large skillet, heat 6 TBS olive oil. Brown the veal, several pieces at a time and transfer to casserole, standing the pieces of top of the vegetables. The meat should fit into the pan in one layer. Brown remaining veal, adding more oil if necessary.
Discard all but 1 TBS oil from skillet. Add the wine and boil briskly until it is reduced to 1/2 cup. Stir in the chicken broth, basil, tomatoes, parsley and bay leaves. Bring mixture to a boil and pour over the veal. Bring the casserole to a boil on top of the stove. Cover and place in oven, basting occasionally. If necessary, regulate the heat slightly to maintain a constant simmer. Bake for one hour and 15 minutes, or until the meat is tender. Combine the gremolata ingredients. To serve, arrange the veal shanks on a platter and spoon the sauce and vegetables around them. Sprinkle the top with the gremolata. 6 servings.